Former President George W. Bush has a number of accomplishments under his belt : Texas governor , U.S. president , and now , a New York Times best-selling author .

But even though Bush 's book about his father -- `` 41 : A Portrait of My Father '' -- has been No. 1 on the Times ' nonfiction sellers list for weeks , Bush admits the book is n't exactly a historical biography .

`` It 's a love story , '' Bush told Candy Crowley on CNN 's `` State of the Union . ''

`` I 'm not the least bit ashamed to say it 's not very objective , '' he added . `` I also happen to think it 's a handbook on fatherhood . If somebody 's interested in how a person was a great father , even though he 's very busy , this book is such an example . ''

Bush ` wanted Dad to be alive ' to read biography

In the interview , Bush jokes that neither he nor The New York Times had any idea that his book would become a best-seller .

But the former president did n't write the book with sales in mind . Instead , he says , he felt the need to publish his father 's story , to reintroduce his dad to America in a way that no one has ever known him .

`` He 's an extraordinary person , not only because of his accomplishments but because of his character , '' Bush said . `` I understand how history works ; It takes a long time for people to get to know him , get to know somebody and then analyze their decisions . But I wanted to be one of the first people out in the evaluation of George H.W. Bush . ''

Bush also tried to dispel any rumors of competition between him and his father .

41 things about Bush 41

`` Stiff competition is overstated , '' Bush said . `` In other words , if you love somebody as much as I love my dad , and my brothers loved my dad , my sister , there 's no need to compete . ''

The fact that the elder Bush is still alive to see the book also meant a lot to him , Bush said .

`` I 'm glad Dad 's alive when it comes out , '' he said . `` Secondly , I 'm glad that a lot of his friends are alive and can take it in and say , ` wow , this is the guy I know . ' ''

Bush picks Jeb over ` sister-in-law ' Hillary in 2016

@highlight

George W. Bush calls his new book on his father `` a love story ''

@highlight

Bush says his father , George H.W. Bush , is an `` extraordinary person ''